Cmdr. Mohamed Douhane of police union Synergie described the rioting to ABC News as "open rebellion," with youths operating like "urban guerrillas."

"We are dealing with groups of louts who are very mobile, very determined, and who are not hesitating to use firearms to shoot at policemen like rabbits," he said.

About 100 young men set fire to cars and several buildings in the suburb of in Villiers-le-Bel, 12 miles north of the French capital. The fire service quickly arrived on the scene and was able to control most of the flames.

The only building to suffer serious damage was the local public library. Some of those rioting Monday night were said to have been as young as 10 years old.

Riot police responded with tear gas and rubber bullets.

Monday's rioting came a day after two teenagers were killed in a traffic accident involving a police vehicle in the same suburb of Villiers-le-Bel. Police have said that a
15-year-old and 16-year-old were riding on a small motorbike that collided with a police car out on a routine patrol.

Their deaths sparked riots Sunday in Villiers-le-Bel, and the surrounding areas of Gonesse, Sarcelles and Arnouville. Around 30 cars and several buildings were set ablaze. Eight arrests were made, and 20 police officers were injured.

A preliminary investigation by police Monday appeared to clear the officers of responsibility for the road accident.

French Prime Minister François Fillon said today that "those who fire on the police are criminals. They will be treated as such," saying that additional security forces would be deployed in the Parisian suburbs Tuesday night.

Yesterday's riots are reminiscent of the violence that swept across Paris' outlying suburbs in the autumn of 2005 and spread to the rest of the country. Those, too, were sparked by the deaths of two youths, electrocuted in a power substation while hiding from police.

So far, the riots over the past couple of days have been much smaller in scope but more intense, according to police.

"Violence against the police has radicalized itself, with a quasi-systematic use of firearms," Douhane told ABC News.

"This is a new development, compared to the riots of two years ago. In 2005, there were two shots fired at the police, but that was after several weeks of violence; 77 policemen were wounded last night, while in 2005, during three weeks of violence, a total of 126 policemen and gendarmes were wounded."

Monday youths built improvised barricades out of trash cans and rubble. Eyewitnesses described the rioters as organized and disciplined.

Sebastian Roché, a sociologist and author at think-tank CNRS, agreed. He told ABC News that "the rioters have learned from 2005. They use garbage covers as shields. Some are very determined, and are prepared to use weapons that can kill. The violence has reached a new level."

Monday night one youth was seen with a two-way radio tuned in to a police frequency.

Sebastian Roché believes that it's too early to know if the violence will spread. Police representatives told ABC News that the potential for further escalation "is of great concern."

Three local mayors said that the situation in the suburbs since 2005 had not only failed to improve but has indeed worsened. "In the autumn of 2005, French politicians seemed to wake up to the serious problems in the suburbs," wrote Claude Dilain, Stéphane Gatignon and François Pupponi in the daily newspaper Le Monde.

"Yet the situation continues to deteriorate. All the data points to increases in social exclusion, unemployment, street violence … communities are unravelling, and when people feel abandoned, they have a tendency to turn in on themselves."

ONZUS, a government agency that monitors urban areas, confirmed that despite a small drop in crime since 2005, unemployment in these neighborhoods remained twice as high as the national average.

France's political parties, and the families of the killed teenagers, have condemned the latest violence and urged for calm. While on an official visit to China today, Nicolas Sarkozy called for the justice system to take its course and determine who is responsible.

Wednesday the French president is expected to visit injured police officers in the hospital, meet the families of the killed teenagers and convene a meeting of ministers to discuss his government's response.

As Interior Minister during the 2005 riots, Sarkozy caused considerable controversy when he declared that the restive suburbs needed "cleansing," and described the youths as "rabble."

Police commander Mohamed Douhane told ABC News today that a minority of young people in the French suburbs reject state institutions, and the police in particular. "They use an excuse, a tragic event in this case, to express their hatred of society by the most violent means."